61-04-04: Landing Gear Drag Strut Plates

61-04-04 LOCKHEED: Amdt. 251 Part 507 Federal Register February 10, 1961. Applies to All Models PV-1 and B-34 Aircraft With Main Landing Gear Drag Strut Attach Plates, P/N 112900 or P/N 12665. Compliance required as indicated. (It will be necessary for operators to maintain a record of landings in order to ascertain compliance with this AD.) Investigation has shown that failure of the main landing gear drag strut attach plate, P/N 112900 has caused the main landing gear to collapse. The B-34 main landing gear drag strut attach plate, P/N 12665, is the same as the PV-1. As a result of this service experience the following shall be accomplished: (a) Inspection in accordance with either (1) or (2) is required: (1) Within the next 25 landings and every 50 landings thereafter, inspect the main landing gear drag strut attach plates, P/N 112900, or P/N 12665, in place on the aircraft for cracks and looseness.* Dye penetrant or FAA approved equivalent must be used for crackdetection. If the drag strut attach plate is loose, then it must be visually inspected for elongation of the bolt holes and the attaching bolts visually inspected for cracks, or deformation. If cracks or elongation of the bolt holes are found in the drag strut attach plate, it must be replaced prior to the next flight. Deformed or cracked bolts must be replaced prior to the next flight. (2) Within the next 25 landings, unless already accomplished within the last 125 landings and every 150 landings thereafter, remove the main landing gear drag strut attach plates, P/N 112900, or P/N 12665, and conduct an X-ray or dye penetrant, or FAA approved equivalent, inspection for cracks. The bolt holes in the drag strut attach plate must be visually inspected for elongation and the attaching bolts inspected for cracks or deformation. If cracks or elongation of the bolt holes are found in the drag strut attach plate, it must be replaced prior to the next flight. Deformed or cracked bolts mustbe replaced prior to the next flight. (b) The special inspections contained in this AD may be discontinued after the Howard Aero, Inc., replacement main landing gear drag strut attach plates, P/N 5-302006, or FAA approved equivalents, are installed using 180,000 p.s.i. minimum ultimate tensile strength attaching bolts. This directive effective March 14, 1961. *A method of inspection for looseness is to check for gaping of 0.010 inch or greater, between the drag strut plate and the backing plate at a point approximately 4.5 inches above the lower edge of the attach plate. Insert a feeler gage between the attach plate and the backing plate from the outboard side to make this check.